Hundreds of marijuana plants growing at a 40-acre operation in the Madera County foothills were seized by a narcotics task force Thursday, authorities reported.

No growers were present when the officers arrived, said Erica Stuart, a spokeswoman for the Madera County Sheriff’s Office.

Greenhouses – some nearly the size of a football field – were set up on the property, Stuart said in a press release. She said each marijuana garden on the property contained hundreds of fully budded marijuana plants.

She also said in the release that a shed at the site was already filled with hundreds more plants ready for processing. Narcotics agents confiscated more than 500 plants.

Animal-control officials were called to rescue a dog chained to a tree on the property.